A federal appeals court heard arguments today over Utah's gay marriage ban. It's the first time the issue has come to appeal since the Supreme Court overturned a key part of the Defense of Marriage Act last summer. Several other states - Texas, Michigan and Oklahoma among them - have also seen their marriage bans overturned in federal court. But the Utah case is the furthest along and it's playing out in the 10th Circuit court in Denver.

That's where Colorado Public Radio's Megan Verlee spent the day. And, Megan, start by explaining the basics of this case, the arguments from each side.

MEGAN VERLEE, BYLINE: Well, both sides in this case leaned heavily on that recent decision you just mentioned in the Defense of Marriage Act known as the Windsor case. On one side, you had an attorney representing three Utah couples who wish to marry in the state are trying to strike down a constitutional ban on same-sex marriage. Their attorney found language in the Windsor decision that supported the idea that marriage is a fundamental right and it's protected by the U.S. Constitution above and beyond any laws that states might pass.

But on the other side, the attorney for the state of Utah argued that Windsor actually supports a federalist approach to marriage, where the states are the ones that have the overriding power to set their marriage laws. And after the arguments, Utah attorney general, Sean Reyes, came out and spoke to the media, and he emphasized that line of reasoning.

SEAN REYES: This case fundamentally is about the right for a state like Utah to be able to determine something as significant and fundamental as marriage through the democratic process.

CORNISH: Megan, legal analysts often look to the line of questioning from the judges to get a sense of what they're thinking. What were they most interested in?

VERLEE: Well, it seemed like they were very concerned about this question of what kind of scrutiny they should give Utah's marriage laws. Whether they should look at it with what's called a rational basis, which is where the burden of proof is on the group that's being discriminated against by the law to show that they're being harmed unfairly and with animus, with malice, or to give it heightened scrutiny where the burden of proof would then be on the state of Utah to show that it had such an overwhelming interest in defending the traditional definition of marriage that it could make a law that harmed gay couples.

And the big question here is that the Supreme Court has never really ruled definitively around whether laws that affect gays and lesbians should get that heightened scrutiny or if they should get a lower level of attention.

CORNISH: Meanwhile, the state of Utah changed its legal strategy. Can you help us understand what happened there?

VERLEE: Yes. Last evening, they filed a note with the court saying that a study that they relied on in footnotes to show that children in same-sex couples do not do as well as children in heterosexual married families - and hence, the state had an interest in supporting heterosexual marriage - that they were backing off from that study. And it probably has a lot to do with the fact that a Michigan judge in a ruling overturning that state's gay marriage ban called testimony by the study's author, sociologist Mark Regnerus, entirely unbelievable and not worthy of serious consideration.

Utah said, hey, we have other studies that show there's a concern here, but in general, the sociological data is not certain and the judges can make what they want of it.

CORNISH: Megan, the Utah case is just the first of many marriage equality cases moving through the federal system. Can you give us an update on the others?

VERLEE: Well, this same 10th Circuit court will actually be hearing a challenge to Oklahoma's gay marriage ban next week and is expected to rule on both states' laws at once. There are also cases moving into the appeals system in Michigan, Texas and Virginia. So we're looking at three or four circuit courts likely having rulings on these marriage laws fairly soon, which means that it's incredibly likely that the Supreme Court will have to take up this issue and rule definitively on gay marriage. And they could do that as soon as their next session.